BOSTON — A new poll shows Democratic incumbent Deval Patrick opening up a double-digit lead over his Republican challenger in this year’s Massachusetts gubernatorial race, and independent candidate Timothy Cahill plummeting in the aftermath of a GOP advertising barrage.
A Suffolk University/WHDH-TV survey released Tuesday showed Patrick leading Republican Charles Baker 42 percent to 29 percent, a margin of 13 points. A similar survey in February had Patrick ahead 33 percent to 25 percent, an 8-point margin.
The poll also showed Cahill, the state’s treasurer, dropping after the Republican Governors Association targeted him with a $1 million negative advertising campaign. He had the support of 14 percent of those surveyed, compared with 23 percent in February.
The GOP has been concerned that Cahill, a former Democrat, could attract the same fiscally conservative voters Baker is targeting.
“Tim Cahill’s decline has been a clear net positive for Gov. Patrick,” said David Paleologos, director of the Suffolk University Political Research Center. “Patrick is the better-known alternative, is trusted the most and is perceived to have run the best campaign thus far. More than 60 percent of voters still have no opinion of Charlie Baker or have never heard of him, so he hasn’t given voters a reason to choose him.”
The fourth person in the race, Green-Rainbow Party candidate Jill Stein, had 8 percent of the vote, an improvement of 5 percentage points since February. Seven percent of respondents said they remained undecided.
Suffolk surveyed 500 Massachusetts registered voters from Thursday to Sunday. The poll had a sampling error margin of plus or minus 4.4 percentage points.
Patrick’s campaign manager, Doug Rubin, attributed the growth to recent signs of improvement in the Massachusetts economy, including the addition of 19,000 jobs in April. The survey found 45 percent of voters said the economy is improving, while 49 percent said it is not.
“And I think we’re seeing people responding to some of the work this administration has done over the past three years,” said Rubin. “But there’s still a long way to go, and a lot more work to do.”
Rubin also questioned whether Patrick is benefiting from the anti-Cahill ads.
“People forget that we’re featured prominently in those ads, so it would be ironic if the RGA ran negative ads against the governor and we benefited from them,” he said. “I do think people are fed up with negative ads, especially six months before an election, and they may have backfired on Baker and the RGA.”
Cahill’s campaign manager, Adam Meldrum, said the results should be expected after a campaign “smearing Tim Cahill’s record with dishonest attacks.”
He added: “If they want to run a negative campaign, that’s fine, but we still have more money in the bank than anyone in this race, and are the only candidate with a proven record of fiscal responsibility and fighting for the middle class.”
A Baker spokesman declined comment.
In the survey, Patrick led Baker among men (39 percent to 30 percent), women (45 percent to 29 percent), white voters (40 percent to 30 percent), minority voters (56 percent to 24 percent), as well as in every region of the state.
Among independents, Baker led Patrick by 35 percent to 26 percent, far less than the 64 percent to 29 percent advantage among independents Republican Scott Brown had over Democrat Martha Coakley in a Suffolk poll just before their January Senate special election.
The poll also surveyed voters on two possible tax-cutting ballot measures.
Some 49 percent said they support an initiative petition proposing to reduce the sales tax from 6.25 percent to 3 percent. Forty-four percent said they oppose it, while 7 percent were undecided. The findings were identical to those in the February Suffolk poll.
Voters also supported retracting last year’s extension of the sales tax to alcohol by a margin of 48 percent to 43 percent. That was a smaller margin than the 54 percent to 39 percent found in February.
Voters said they supported allowing casinos in Massachusetts by a margin of 54 percent to 39 percent, almost identical to the 57 percent to 34 percent margin in February.